I. Field of the Invention
This invention relates to a retrievable packer for a well bore and, in particular, to a packer which is set within the well casing hydraulically, released mechanically for retrieval, and includes load transfer means to maintain secure setting and equalization means for proper release of the packing tool.
II. Description of the Prior Art
Well packers and similar well devices have been widely used in oil, gas and geothermal production to separate specific regions of a well bore. Prior packers include permanently set packing devices which are left within the will and temporary or retrievable packers which can be removed for further production. Generally the packers include one or more elastomeric elements to seal off the bore and at least one set of slips to set the device within the cased bore. The principal disadvantage of previous designs for retrievable well packers is that they are expensive to manufacture or to use due to the large number of components. Many require special devices for setting and/or retrieving the device.
Furthermore, with the increased depth of exploration and production, increased well temperature and pressures are encountered. The slip assembly and packing elements of many of the prior known packing devices are designed for nominal well pressures. As downhole pressures increase the ability of the slips and packing elements to hold the well casing decreases which could result in blowout of the packer and, at the very least, creeping of the packer from its original position. Either result can lead to a dangerous situation and lost production.